1. Field of the Invention
The present invention relates to thermal printing techniques, and more particularly, to driver circuits of a thermal sublimation/transfer printer, the control methods thereof and related thermal print heads.
2. Description of the Prior Art
In general, color printers can be classified into four major categories: dot matrix printers, inkjet printers, laser printers, and thermal sublimation (or thermal transfer) printers. Recently, the thermal sublimation printers have become increasingly popular due to their full tone printing performance. A thermal printer drives its thermal print head (TPH) to heat ribbons containing dyes. The dyes of the heated ribbon are transferred onto the object to be printed. By this way, continuous-tone can be formed on the object according to the length of the heating period or heating temperature.
Please refer to FIG. 1, which shows a schematic diagram of a conventional thermal print head 100. As shown, the thermal print head 100 is provided with a plural of driver circuits 110. Each driver circuit 110 loads printing data in accordance with an operating clock signal and then latches the loaded data under the control of a latch signal. Afterward, a strobe signal is employed in the thermal print head 100 to control each driver circuit 110 to drive plural coupled heating elements. Each heating element is arranged for heating an image dot, i.e., a pixel of the image to be printed. While the thermal print head 100 prints pixel data of a row, all driver circuits are controlled by the strobe signal to simultaneously drive corresponding heating elements. Therefore, considerable power consumption is required for supporting the operation of the thermal print head 100.
One conventional method for reducing the power consumption of the thermal print head 100 is to divide the image data of a same row into two parts: one part is composed of odd pixels while the other part is composed of even pixels. Then, the two parts are printed in turn. For example, the thermal print head 100 can firstly print odd pixels of a row and then print even pixels of the row after the odd pixels are completely printed. Such a printing method can reduce the required power consumption of the thermal print head 100, but it requires twice the printing time and increases the complexity of the firmware control of the thermal sublimation printer.